It does to some extent, too. But besides dune crests, both bedrock cracks and the boundary between sand and bedrock count as edges, so as long as the bedrock contrasts with the sand, and it is cracked, there's actually more density of edges at bedrock than anywhere else.

I have a theory. There are a lot of blueberries in the pavement where the ripples are sparse and tiny. Out where they start looking like a dune sea, the ripples seem to be emplaced directly onto the top of the sulphate-rich bedrock. There does not seem to be a layer of blueberry paving between the ripple bases and the exposed bedrock out in the extensive ripple fields.

I think the surface around the landing site and Endurance was derived from a blueberry-rich strata, laying down a bedrock-capping pavement which by some mechanism inhibits deep ripple formation. As you move south, the land rises and the near-surface bedrock layers are blueberry-poor, no capping pavement is generated, and ripples form bigger and taller, growing to almost completely cover the bedrock onto which they are directly emplaced.

Near large craters like Victoria, the local soils surrounding the crater are derived from the geologically rapid erosion of the ejecta blanket, and all of the ejecta nearest the crater is derived from lower, blueberry-rich strata. Thus, in the soils right around a Victoria-sized crater in this area, a blueberry pavement forms and ripple creation is inhibited.

I'd feel better about this theory if I could think of a plausible mechanism by which the blueberry pavement inhibits ripple formation...

-the other Doug

The process Doug is referring to here is called "armoring" in sedimentology. When larger or more dense grains or clasts are left behind during winnowing or deflation, they create a pavement lag. This lag protects the underlying sediment from further erosion. In the case of blueberry-armored areas, it eliminates a local source of potential sediment supply for dune bedforms...the sediment must come in from a more distant source. Outsized grains or clasts on the surface also act to disrupt the atmospheric boundary layer, protecting finer grains between the clasts from encountering flows that exceed the critical shear stress needed for movement. Sedimentologists call this effect "hiding". The dunes themselves act to disrupt the boundary layer, creating flow separation and re-attachment zones which, in turn, are what control dune shape, height, and migration rate.

Thanks for that explanation!

I was wondering why there is more pavement exposed in the larger dune areas compared to the smoother areas?
Is this due to wind scour in the intradune areas? (Due to turbulence in the boundary layer?)

-Mike

Here's a graphical representation of Doug's hypothesis:
Click to view attachment

-Mike

On a baby scale we can see this when we see old and new rover tracks together. The new tracks have pushed the berrys into the underlying soil. This exposes the underlying soil, so you come back a year later, and the wind has blown that re-exposed soil away and the berrys look like they're growing back out of the soil again.

Doug

I wonder if this effect could be used for the terrain analysis in the Meridani region?

Areas with more exposed blueberries should then correlate to areas with more cohesive sand. Areas with fewer exposed blueberries, looser sand.

CRISM hematite signature or HiRise Blue images might be neat to incorporate into the current models.

-Mike

Speaking of dunes, the dunes of Meridiani, according to a post at universetoday.com, or rather the sulfate bedrock ones are referred to as TARs (Transversal Aeolian Ridges) and may hold a record of climatic conditions for the past few million years.

TARs facts in a nut shell.

-occur mostly in the southern hemisphere and concentrated at the equator (comparable to the position of Titanian dunes).
-occur in only TWO environments; near a large source of basaltic sand and on flat sedimentary bedrock e.g meridiani planum. The former are more active but the former are rather inactive hence they date back millions of years ago.
-lastly, there are no comparable terrestrial equivalent (so no playing with analogy ), Why? a mystery.

BTW, Juramike, yes CRISM data would be a useful addition to the outstanding modeling you have been doing. Why didnt I think of that?

...which implies that, if you had CRISM data of fine enough resolution, it would aid a driveability analysis in Meridiani Planum and other similar landforms.

Thanks everyone, especially Tim and Mike, for explaining and illustrating the mechanism I was looking for. Quite obviously, this theory wasn't something that occurred to me before anyone else... -- not that I was arrogant enough to think so. But it's nice to see that there is a good, solid mechanism underpinning the observation.

-the other Doug

Click to view attachment

Im trying to use ImageJ software to come up with another way to perform drivability analysis. Its mostly for dune distribution and size. Its not perfect per se but atleast....

The above image shows the distrbution of EXTREMELY DANGEROUS dunes ONLY at Oppy's position at the time (Sol 1702) in 3d view. Please ignore the scaled axes, they dont mean anything. This is just to show the capability of my techniques (baby steps though). Refer to Tesheiner's latest map of sol 1702.

I'm going to try to relate the UMSF Terrain Models to some of the observables made by Opportunity.
It'd be spiffy-nifty if some of the models can predict soil cohesiveness.

For each Sol, I'll use the normalized grayscale value of a 10 m x 10 m square based on Oppy's position (from Eduardo's route map) for each of the Terrain Models.

For the observables I'll use:

• Hazcam Rover Track "Star" Pattern appearance
• Hazcam Rover Track Tread impression
• Hazcam Rover Track Rut Depth
• Estimated Dune wavelength
• Estimated Dune Height/wavelength
• Estimated Dune Height
• Oppy Report: m driven that day
• Oppy Report: %reported slip for that day

Some of these will be pretty subjective so I will use a 1-3-5 rating system. (1=good; 5=bad)

I'll make a Big Table O'Data and see if there is a good correlation.

-Mike

Here is the 1-3-5 subjective grading system for the RoverTrack Star Pattern appearance:
(the "star pattern" is the tread impression that is noticeably different from the normal tread)
1 = star pattern is crisp
3 = star pattern is blurred
5 = no detail is visible in the star pattern (star pattern is not discernable)

Examples of Hazcam images for three different terrain types (Green, Blue, and Red) that exemplify the 1-3-5 grading scale for the Star Pattern appearance:
Click to view attachment

(These same images can be used to set the grading for some of the other criteria listed above)

-Mike

Here is the 1-3-5 subjective grading system for the RoverTrack Tread impression:
Click to view attachment

Grading scale
1 = tread pattern is crisp
3 = some blurring or lifting sliding of rectangle tread patterns
5 = tread pattern is chunked with extensive sliding and tread pattern destruction

-Mike

Here is the 1-3-5 subjective grading system for the RoverTrack Wheel Rut Depth:
Click to view attachment

Grading scale
1 = outer edge of track not visible (no rut or sinking into substrate)
3 = edge is visible, wheel slightly sinks into substrate
5 = edge is blurred or ragged, hubcap covered (not good!)

-Mike

I tried to estimate the dune wavelength based on visible "yardsticks": the rover wheel track width and the star pattern spacing (wheel circumference).

Does anyone have good numbers for the wheel track width or the star pattern spacing?


Here are the same exemplified Sols' Navcam images showing the dune spacing relative to either track width or star pattern spacing:
Click to view attachment

And here is a VERY rough and inaccurate guess of height vs. dune width for Navcam images from the same Sols. (This may be very suspect due to the perspective changes).
Click to view attachment


-Mike

Here is the scorecard for Sol 1687 observables:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1687 position:

HiRise (raw): 98.91
HiRise (normalized): 41
Malaska 20081003 normalized grayscale Terrain Model: 38.64
Canvin 20081001 normalized grayscale Terrain Model: 47.67
Ontanaya 20081001 normalized grayscale Terrain Model: 110.08
Butler 20081006 normalized grayscale Terrain Model: 3.47
Sassen 20081031 normalized grayscale Terrian Model: 35

-Mike

Here is the scorecard for Sol 1691 observables:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1691 position:

HiRise (raw): 104.11
HiRise (normalized): 71.81
Malaska 20081003 normalized grayscale Terrain Model: 70.39
Canvin 20081001 normalized grayscale Terrain Model: 78.81
Ontanaya 20081001 normalized grayscale Terrain Model: 72.97
Butler 20081006 normalized grayscale Terrain Model: 79.42
Sassen 20081031 normalized grayscale Terrian Model: 39.8

-Mike

Here is the scorecard for Sol 1693 observables:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1693 position:

HiRise (raw): 105.34
HiRise (normalized): 82.63
Malaska 20081003 normalized grayscale Terrain Model: 140.47
Canvin 20081001 normalized grayscale Terrain Model: 148.81
Ontanaya 20081001 normalized grayscale Terrain Model: 142.17
Butler 20081006 normalized grayscale Terrain Model: 98.45
Sassen 20081031 normalized grayscale Terrain Model: 103.91

-Mike

Here is the scorecard for Sol 1695 observables:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1695 position:

HiRise (raw): 121.16
HiRise (normalized): 160.84
Malaska 20081003 normalized grayscale Terrain Model: 164.03
Canvin 20081001 normalized grayscale Terrain Model: 187.61
Ontanaya 20081001 normalized grayscale Terrain Model: 107.58
Butler 20081006 normalized grayscale Terrain Model: 121.97
Sassen 20081031 normalized grayscale Terrain Model: 155.55

-Mike

Here is the scorecard for Sol 1697 observables:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1697 position:

HiRise (raw): 117.88
HiRise (normalized): 140.78
Malaska 20081003 normalized grayscale Terrain Model: 191.11
Canvin 20081001 normalized grayscale Terrain Model: 187.61
Ontanaya 20081001 normalized grayscale Terrain Model: 231.06
Butler 20081006 normalized grayscale Terrain Model: 116.17
Sassen 20081031 normalized grayscale Terrain Model: 185.47

-Mike

Wait a second. I must be missing something important in this discussion. The armoring of sedimentary bedforms protects them from further erosion, but it doesn't prevent them from future burial, which I thought O'Doug was proposing. ("a plausible mechanism by which the blueberry pavement inhibits ripple formation...")

I can see how Victoria's annulus is protected from erosion by it's blasted out, remnant blueberry armor, but what prevents the annulus from being buried by the large, migrating ripples surrounding it. It's apparently been a long time since the large ripples have migrated, but I must suspect some other variable is responsible for the parking lot topography of the annulus. Might it be that the concentration of concretions actually enhances the flow boundary affects you speak of to encourage sediment grains to move past this area?

I think the important effect of armoring is to prevent local sediment from beneath the armor from deflating and contributing to dune formation. It does not prevent dunes from migrating onto the armored area from upwind zones of less limited sand supply. However, once dunes encroach onto the edge of the armored area, they would begin to be increasingly sand limited. In a more regional sense, these areas of sand limited areas down-wind of sand seas are called fore ergs. The sand limited area upwind of a sand sea is called a back erg. The encroachment of the terrestrial dunes in the Sahara into the Sahel today is a good analog.

I think one of the other important factors related to Martian ripple/dune field origin and evolution is the duration of a particular long-term dominant wind direction. We all have been struck by the regularity of ripple/dune crest orientation in the MER and orbital images. I am curious as to how the Milankovich-related changes in Martian climate, especially dramatic changes in obliquity and precession are tied to the evolution of these features.

Here is the scorecard for Sol 1700 observables:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1700 position:

HiRise (raw): 118.92
HiRise (normalized): 147.39
Malaska 20081003 normalized grayscale Terrain Model: 186.52
Canvin 20081001 normalized grayscale Terrain Model: 208.27
Ontanaya 20081001 normalized grayscale Terrain Model: 165.95
Butler 20081006 normalized grayscale Terrain Model: 176.39
Sassen 20081031 normalized grayscale Terrain Model: 204.75

-Mike

Here is the scorecard for Sol 1702 observables:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1702 position:

HiRise (raw): 145.70
HiRise (normalized): 228.23
Malaska 20081003 normalized grayscale Terrain Model: 186.19
Canvin 20081001 normalized grayscale Terrain Model: 173.16
Ontanaya 20081001 normalized grayscale Terrain Model: 142.24
Butler 20081006 normalized grayscale Terrain Model: 178.48
Sassen 20081031 normalized grayscale Terrain Model: 155.42

-Mike

Pulling all the predicted and observable data together for Sols1687-Sol1702 (and adding Sol1704 preliminary data) into a big EXCEL spreadsheet, we get:
Click to view attachment

-Mike

Taking the information in the spreadsheet above, and trying to represent it into a confusing graphic, we get:
Click to view attachment

(scan across like colored/shaped boxes to see how they interrelate on a relative scale)

Preliminary interpretations:

• RoverTrack Rut Depth does not necessarily correlate with Terrain type
• HiRise image values (raw or normalized) do not correlate with either terrain type or RoverTrack observables
• RoverTrack Rut Depth *may* be the more sensitive indicator of soil cohesiveness
• RoverTrack Cleat (star) pattern *may* be correlated to RoverTrack Rut Depth (thus slightly less sensitive indicator of soil cohesiveness)
• RoverTrack Tread pattern may be the least sensitive indicator of soil cohesiveness

With these limited observations, the best predictor of a combination of Terrain type AND soil cohesiveness is (drum roll please.....) the James Canvin FT Terrain Model. (Note the high value for Sol 1697 even though it is still Magenta terrain). The Malaska Shift-Differential Model is second, followed by the Butler Terrain Model.

As Oppy moves into different types of terrain, it will be interesting to see how the different Terrain models correlate with the next part of Oppy's track.

-Mike

Scorecard for Sol 1704:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1704 position:
HiRise (raw): 134.11
HiRise (normalized): 210.22
Malaska 20081003 normalized grayscale Terrain Model: 158.20
Canvin 20081001 normalized grayscale Terrain Model: 168.59
Ontanaya 20081001 normalized grayscale Terrain Model: 113.38
Butler 20081006 normalized grayscale Terrain Model: 142.63
Sassen 20081031 normalized grayscale Terrain Model: 168.50

-Mike

Scorecard for Sol1707:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1707 position:
HiRise (raw): 120.14
HiRise (normalized):160.58
Malaska 20081003 normalized grayscale Terrain Model: 162.86
Canvin 20081001 normalized grayscale Terrain Model: 134.58
Ontanaya 20081001 normalized grayscale Terrain Model: 102.58
Butler 20081006 normalized grayscale Terrain Model: 135.63
Sassen 20081031 normalized grayscale Terrain Model: 117.56

-Mike

Scorecard for Sol1709:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1709 position:
HiRise (raw): 136.66
HiRise (normalized):207.27
Malaska 20081003 normalized grayscale Terrain Model: 180.73
Canvin 20081001 normalized grayscale Terrain Model: 161.50
Ontanaya 20081001 normalized grayscale Terrain Model: 121.30
Butler 20081006 normalized grayscale Terrain Model: 165.28
Sassen 20081031 normalized grayscale Terrain Model: 193.53

-Mike

Scorecard for Sol 1710:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1710 position:
HiRise (raw): 149.13
HiRise (normalized):236.77
Malaska 20081003 normalized grayscale Terrain Model: 173.05
Canvin 20081001 normalized grayscale Terrain Model: 160.69
Ontanaya 20081001 normalized grayscale Terrain Model: 156.80
Butler 20081006 normalized grayscale Terrain Model: 184.53
Sassen 20081031 normalized grayscale Terrain Model: 79.38

-Mike

Some digging in the literature:

Found a really helpful abstract that answers a lot of these questions:
Sullivan et al. LPSC 38 (2007) Abstract 2048. "Aeolian geomorphology with MER Opportunity at Meridiani Planum, Mars." (freely available here)

And a Nature article that describes aeolian processes evidenced by Opportunity:
Sullivan et al. Nature 436 (2005) 58-61. "Aeolian processes at the Mars Exploration Rover Meridiani Planum landing site" doi: 10.1038/nature03641. (Pay-for article: abstract available here)

And just a really nifty explanation of Sand Dune Geology:
http://www.nps.gov/archive/whsa/Sand%20Dune%20Geology.htm


Here' a quickie summary of the story at Meridiani Planum (and a modified diagram to fit the explanations in the articles):
Click to view attachment


Areas near Eagle and Endurance had more (and bigger) blueberries exposed as the leftover (=lag) deposit after soft rocks were blasted (=eroded) away by wind.
The blueberries armored the remaining surface and prevented bigger ripple formation. (tdemko's explanation of armoring here)

To the S, near Erebus and Victoria, the surface strata did not have as many blueberries (and they were smaller).
The windblown sands blasted the easily eroded sulfate-rich surface rock into flat pavement.
Big dunes heaped up.

At Victoria annulus, the deeper blueberry rich strata got blasted up and landed in a ring of blueberry rich rocky chunks immediately around the crater. Over time, the rocks got blasted away and left the blueberries on the surface as a lag deposit. Again, armoring from the blueberries prvented big ripple formation.

All this happened long, long ago. The wind directions back then left dunes and ripples oriented in N-S (and later SW-NE) lines.
These big winds formed the winds in their current orientation.
The big dunes outside the craters are not currently mobile. They are very old.

Current winds are either NW to the SE.
The current winds blow loose dark basaltic sands (from somewhere else) around and across the Meridiani dunes.
They get temporarily trapped in the crater bottoms, then get blown out. The blown out dark basaltic sands form the transient "dark streaks", like we saw at Victoria Crater.
(The current winds are actively forming ripple patterns in the dark basaltic sands at the bottoms of the craters.)
(Current winds are also blowing dark basaltic sands along the dune troughs as they migrate from one dust trap to the next.)

Bright airfall dust is also being transiently deposited in the lee of the crater rim in the downwind direction. (A change in wind direction and *poof* it's gone!).

Older filled-in craters are big traps for migrating sands.
The sands get blown out of the craters but then are redeposited in the lee at the upturned rim.
The result is big dunes with smooth rock pavement around the rime of the old craters (like at Erebus).
The larger ripples/dunes along the rim can also temporarily trap bright airfall dust. Result: bright rims of the craters (either from exposed pavement between dunes or temporarily trapped dust in the lee of the locally larger ripples).

-Mike

Thanks for the summary! Are there any ideas why the large plains dunes are now frozen? Stronger winds in the past? Or were their surfaces cemented somehow?

Fredk,
As i said previously in this thread, the meridiani dunes are a type of transversal aeolian ridges (TARs) which do not move mostly because they are now difficult to move and partly because of there being a lack of a 'source' of the sand.

The other type are basaltic and are usually located near a source, and since they are easier to handle, they move about quite a lot.


Fredk,
As i said previously in this thread, the meridiani dunes are a type of transversal aeolian ridges (TARs) which do not move mostly because they are now difficult to move and partly because of there being a lack of a 'source' of the sand.

The other type are basaltic and are usually located near a source, and since they are easier to handle, they move about quite a lot.

Whoa, talk about deja vu, Doc. In reading your posting, I got this weird feeling like I had read exactly the same thing once before.

Drivability analysis for the whole trip!

Small version overlayed on Tim's map as well as really big versions if anyone is interested.



Endeavour looks amazing!

James

This might be interesting to some of the more mathematically minded people here, and
might be useful for the kind of processing you are looking at.

Mathematica image processing

Very cool stuff...

Chris

I read about that too Chris, definitely worth a look!

Here's another interesting article:

Helmick et al IEEEAC paper #1668. "Terrain Adaptive Navigation for Mars Rovers". (Freely available here)

-Mike

Scorecard for Sol 1711++:
Click to view attachment

For the UMSF Terrain Models, here are 10 m x 10 m normalized grayscale pixel averages for Oppy's 1711 position:
HiRise (raw): 149.77
HiRise (normalized): 246.86
Malaska 20081003 normalized grayscale Terrain Model: 174.02
Canvin 20081001 normalized grayscale Terrain Model: 165.23
Ontanaya 20081001 normalized grayscale Terrain Model: 150.26
Butler 20081006 normalized grayscale Terrain Model: 163.21
Sassen 20081031 normalized grayscale Terrain Model: 97.2

-Mike

Here's a graph of the "observables" for the Sol 1707-1711 (and counting...) track:
(compare with previous graph here)

Click to view attachment

There does seem to be an empirical relationship between the normalized Canvin FT (orange dot), the HiRise value (brown dot) and the normalized HiRise value (red dot) and a loose correlation with the toe cleat (star pattern) impression. When the orange dot is far away from the red dot AND the brown dot is close to the red dot, then the cleat pattern is worse. But I'm way too brain dead after staring at this all evening to try to come up with a qualitative/quantitative relationship....

Here's an attempt at making a Dustmap of Meridiani.

I normalized and grayscaled James Canvin's FT model, then subtracted a normalized HiRise image and added a small offset.
The idea is that the FT indicated waves (bright in FT model) would subtract nicely with dark features (dark windblown basaltic sand migrating from dust trap to dustrap across Meridiani):
Click to view attachment

Here is the GBR(dust) colorized result:
Click to view attachment

The bummer with this method is that big scary dunes are not differentiated much from easy parking lot terrain. They are both colorized blue.
The cool part is that dust areas are indicated in red.
A bonus cool part is that rock pavement (low FT - bright HiRise = neg) is indicated in black (colorized green).
You can see the finger of green up by Victoria crater that almost coincides with Oppy's route.

-Mike

JPEGs of "Dustmap" Terrain model 20081210 available:

GBR colorized (max resolution option is 18 Mb): http://www.flickr.com/photos/31678681@N07/3097440938/
grayscale (max resolution option is 7 Mb): http://www.flickr.com/photos/31678681@N07/3096616731/
(The grayscale version has a nice effect of really indicating all the subtle craterforms in the area)

-Mike

Zoom of Dustmap[FT-HiRise] Terrain Model with Oppy's track from Sol 1691-1711 superimposed:
Click to view attachment

The "green" rock pavement correlates with Oppy's track.

-Mike

Another attempt at a different way of looking for dust traps. This time trying to isolate out Flat Dark filled craters: low value in FT model and low value in Normalized HiRise). Here's the rationale:
Click to view attachment

I used the sum of the normalized grayscale James Canvin FT Terrain model with the normalized HiRise image. After contrast enhancing and a few filtered blurs, the whole thing was inverted, then colorized.

Here is the exact recipe;
Sum (Photoshop "Apply Image"; scale = 1, offset = 0) normalized grayscale James Canvin FT Terrain model with normalized HiRise image
Curve adjustment (0,0; 7,0; 109,40; 154, 120; 200, 240; 230,255)
Filter/Noise/Median 2 pixels
Curve adjustment (0,0; 7,0; 78, 26; 129, 115; 148, 151; 182, 215; 255, 255)
Gaussian blur 1 pixel
Invert image
Colorize using the standard color table

And the result:
Click to view attachment

The smaller bright red splots and circular dots are mostly filled craters. The much larger red regions are areas of low waves and dark sand. These could be "safe" blueberry armored flat terrain.

-Mike

Zoom of Flat Dark dust trap Map Invert[FT+HiRise] Terrain Model with Oppy's track from Sol 1691-1711 superimposed:
Click to view attachment

(Note that Oppy's track Southward from Victoria has not come close to any of the potential flat dark dust traps. So Navcam images in this area can't be used to confirm if this terrain model has any value.)

JPEGs of "Flat Dark Dust Trap" Terrain model 20081214 available at 2 m/pixel resolution (12.5% HiRise):
GBR colorized (max resolution option is 6.3 Mb): http://flickr.com/photos/31678681@N07/3108...57610916194789/
grayscale (max resolution option is 2.5 Mb): http://flickr.com/photos/31678681@N07/3108...57610916194789/

-Mike

In the southern section of the S Victoria Crater HiRise images, there are a series of large scale ripple patterns (26 m wavelength) that are going NNW. (So..crests are WSW to NNE)

I think these are dunes/dust that have moved more "recently" since they are in line with the current prevailing wind pattern. They might indicate a hazard area, or they might be nothing at all.

I spent the last few days trying to "light them up" and indicate them in a model (using the differential shift of 15 E pixels and 50 S pixels) but haven't had much luck getting them away from the normal brightness variation.

Any suggestions?

-Mike

I cannot comment on the age of these ripples (in the sense that it is way above my head). If you are trying to find them, you could try using correlation with a template. Since they are axial symmetric, you could even try a 1D correlation with a Nx1 strip extracted from a manual selection. If you are unfamiliar with correletion, email me and I can give you a quick explanation (unless anyone eslse is interested and want me to post it).

Paolo

I'm interested. Is this an easy step-by-step thing to do in Photoshop?

I don't use Photoshop so I can't comment on that. Correlation is well known machine visoin algorithm so it might be available in Photoshop. If not I can give you a quick explanation on what it means and you could try to implement it yourself.

Paolo

I have finally completed my analysis of the new Endeavor image. I used exactly the same parameters as for my Victoria analysis. Apparently the Victoria image was near the limits of a couple of the tools I used because the new image broke them. But I persevered and found different ways to get it into the processing tool (the actual analysis tool didn't have a problem with the size, although I think it was getting close!). And of course the outputs are larger as well. I did my 64x64 2dfft on every fifth pixel in each direction, and filled the result in all 25 pixels (even so it took 10 hours!). So I can decimate by 5x each way without losing any information at all. That png file is 5961x17628 pixels and 130MB, and I don't know how to post it. The jpgs are of postable size. So I further decimated by 4x each way, and now the files are small enough to be posted to speedyshare, as I did earlier. The links are here (jpgs are on 5x decimated from original, pngs are 20x):

blended image:
http://www.speedyshare.com/714664859.html
(image1a.png)
http://www.speedyshare.com/793846195.html
(image1.jpg)

analysis only in RGB:
http://www.speedyshare.com/725624573.html
(image2a.png)
http://www.speedyshare.com/714399661.html
(image2.jpg)

analysis only as grayscale:
http://www.speedyshare.com/978793399.html
(image3a.png)
http://www.speedyshare.com/604469177.html
(image3.jpg)

original image at same scale:
http://www.speedyshare.com/591706186.html
(image4a.png)
http://www.speedyshare.com/338648594.html
(image4.jpg)

I attach here some previews at yet another 2x decimation and conversion to jpg. I originally used a somewhat more optimistic choice of color scale than James did (which I stuck with for this one), and it makes the Endurance section look like a cakewalk, at least as far as ripples go. I also saw lots of 'Anatolia' features that could be a whole different kind of drivability hazard. Looking forward to the journey!

If anyone wants the larger files and has a place for me to send them, just let me know!

Bill Butler